Conventional drug delivery systems tablets

Drug-delivery systems are essentially specialized dosage forms developed to overcome the limitations of conventional dosage forms, such as simple tablets, capsules, injectable solutions, etc. Some of the reasons behind the development of oral DDSs are listed below ... 

Compared to conventional tablet and capsule dosage forms, solid dispersion formulations are relatively complex drug delivery systems, requiring a substantially greater commitment of time, effort, and resources fordevelopment. Therefore, whetherthere is a need forsolid dispersion and whetherthi... 

Fig. 22 (A) Schematic illustration of Valrelease tablet, a swelling-activated drug-delivery system, and the hydration-induced formation of colloid gel barrier. (B) Comparison in the gastric residence profile between Valrelease with the conventional Valium capsule. (From Ref. l)...

The size of the delivery system varies with the type of formulation, i.e., a buccal tablet may be approximately 5-8 mm in diameter, whereas a flexible buccal patch may be as large as 10-15 cm in area. Mucoadhesive buccal patches with a surface area of 1-3 cm are most acceptable. It has been estimated that the total amount of drug that can be delivered across the buccal mucosa from a 2-cm system in 1 day is approximately 10-20 mg.f The shape of the delivery system may also vary, although for buccal drug administration, an ellipsoid shape appears to be most acceptable. The thickness of the delivery device is usually restricted to only a few millimeters. The location of the delivery device also needs to be considered. A mucoadhesive retentive system is preferred over a conventional dosage form. A bioadhesive buccal patch would appear to be the most appropriate delivery system because of its flexibility and the area of the buccal mucosa available for its application. The maximal duration of buccal drug retention and absorption is approximately 4-6 h because food and/or liquid intake may require removal of the delivery device. 

Buccal dosage forms can be of the tablet, patch, gel, or ointment type and can be employed for local or systemic delivery. For local deliveiy, conventional dosage forms such as solutions and various types of tablets (immediate release, effervescent, etc.) are more suitable. These forms generally have uncontrolled drug release with subsequent variable absorption and short residence times, and may not provide sufficient bioavailability. Novel dosage forms such as adhesive tablets, patches, gels, and... 

---